1. Field of the Invention
The present invention relates to a mobile robot which generally or partly imitates living mechanisms of human beings or animals and, particularly, to a mobile robot which bipedally or quadrupedally freely walks or crawls (in a trackless manner) within a work area or space.
The present invention also relates to a mobile robot that is driven by a rechargeable battery with no umbilical power cable connected, and freely and tracklessly moves within a work space, and to a charging mechanism for charging a battery in the mobile robot. More particularly, the present invention relates to a mobile robot of the type which stops at a charging station for automatic recharging when power remaining in the battery drops during self-controlled operation, and which departs from the charging station to resume normal operation at the end of the charging, and to a charging mechanism for charging the battery in the mobile robot.
2. Description of the Related Art
The term robot is said to be derived from Slavic word Robota (slave machine). In Japan, robots started to be widely used from the 1960s, and most of the robots were then industrial robots such as multiarticulate robot arms (manipulators) and conveyance robots for automating a production line in a plant or for use in an unmanned plant.
Research and development have advanced in moving (ambulatory) robots that use feet in walking and stable walk control for the mobile robots, such as pet-type or toy robots which imitate the living mechanisms and the behavior of four-footed animals such as the dog and the cat, and human-type robots which imitate the living mechanism and the behavior of human beings or apes. Expectations of commercializing these robots are currently mounting. The ambulatory robot is unstable and presents more difficulty in posture control and ambulation control than crawling robots. However, the ambulatory robot is excellent in that the ambulatory robot is flexible in walking and running, for instance, going up and down the stairs, and striding over an obstacle.
An installed robot, such as a robot arm, which is firmly planted at a particular location, is used for the assembling and selection of parts in a limited and local work space only. In contrast, the work space of the mobile robot is not limited. The mobile robot moves along a track or freely on a non-tracked area, performing any predetermined job. The mobile robot thus provides various services, instead of the human beings, the dogs, and other living things.
Humanoid robots coexist under the living environments of human beings, and perform a diversity of simple, risky and difficult jobs involved in the industrial and production activity of the human beings. For instance, the humanoid robots are expected to play an important role in various activities, such as maintenance work in nuclear power plants, thermoelectric power plants, and petrochemical plants, conveyance and assembly operation of parts in production plants, cleaning operations on high-rise buildings, and rescue activities in the site of a fire. The humanoid robot moves around or over an obstacle using the two feet thereof, reaching the site of activity in a self-controlled way, and performs a job exactly as instructed.
The mobile robots for entertainment imitating the dog or the cat, namely toy robots, have the feature of living together in a close relationship, rather than assisting the human beings in difficult jobs. The toy robots are easy to handle, compared with real animals, and offers sophisticated functions, compared with conventional toys.
Conventional toy machines offer fixed interactive relationship with a user operation, and cannot be modified according to the user""s preference. As a result, the user may grow tired of the toy that simply repeats the same operation. In contrast, although the toy robot performs the operation in accordance with time-series action model, the toy robot modifies the time-series action model in response to an external stimulation such as a user operation. Specifically, by imparting a xe2x80x9clearning effectxe2x80x9d to the toy robot, the user enjoys preferable action patterns of which the user is free from being tired.
The toy robot may be programmed to dynamically respond to the user action as an owner, for instance, xe2x80x9cpraisingxe2x80x9d, xe2x80x9cplaying withxe2x80x9d, xe2x80x9cpettingxe2x80x9d, xe2x80x9cstrokingxe2x80x9d, xe2x80x9cchastisingxe2x80x9d, or xe2x80x9cbeatingxe2x80x9d. For instance, the toy robot may respond by xe2x80x9cbeing pleasedxe2x80x9d, xe2x80x9cfawning onxe2x80x9d, xe2x80x9cpoutingxe2x80x9d, xe2x80x9cchastisingxe2x80x9d, xe2x80x9cbarkingxe2x80x9d, or xe2x80x9cwaggingxe2x80x9d. The user thus enjoys an education simulation of the toy robot. The toy robot bipedally or quadrupedally walks within a room at home as a non-tracked work space, moving around or over an obstacle, freely and automatically in a self-controlled manner.
The above-discussed robots are motorized mechanical devices, thereby needing power feeding thereto.
Electric power is supplied from a utility AC supply through a power cable to a robot fixed at a particular location, such as the already-discussed robot arm, or to a robot that moves within a limited radius of action or along a limited action pattern.
It is impossible to feed power to the mobile robot moving around in a self-controlled fashion from the utility AC power supply, because the power cable limits the radius of action of the mobile robot. Self-propelled driving using a battery is a logical choice for the mobile robot. The battery-driven mobile robot runs in a diversity of work spaces, such as a living area of human beings, without any physical limitation such as the location of a wall outlet or the length of power cable.
The battery-driven robot needs battery charging, however. Although the mobile robot is used as an automatic device, a charging operation is an issue that needs to be addressed to construct a fully automatic device. The battery replacement for charging or the connection of a power connector are troublesome to the user.
A xe2x80x9ccharging stationxe2x80x9d has been introduced to perform the battery charging of the mobile robot in a reliable and fully automatic fashion. The charging station provides space dedicated to the battery charging of the mobile robot.
When the robot detects a drop in the power remaining in the battery during the self-propelled and self-controlled operation, the robot suspends the operation thereof, and automatically returns to and stops at the charging station. The charging station establishes electrical connection between the robot and the a power supply thereof, thereby supplying power to the battery of the robot. When the battery is fully charged or recovers the power thereof to a predetermined level, the electrical connection to the power supply is disconnected. The mobile robot departs from the charging station, and resumes the operation thereof that was once suspended.
With a plurality of charging stations arranged within a work space, the mobile robot receives power supplying from the charging station closest thereto. The mobile robot thus moves from station to station for charging, thereby expanding the radius of action thereof. On the other hand, one single charging station may be shared by a plurality of mobile robots. The charging function of the robot may partly be transferred to the charging station, and the required specifications of the robot itself may be made less severe, and the weight and cost of the mobile robot are reduced.
To smoothly and automatically put the mobile robot into a charging operation with the charging station in the middle of a job, the mobile robot needs to be guided into the charging station (or the mobile robot searches for the location of the charging station), while detecting the position thereof and controlling itself for accurate and reliable electrical connection with the power supply.
The mobile robot may be relatively easily set into the charging station if the robot (such as a conveyance robot) moves only along a predetermined fixed track. The charging station is arranged in the midway of the normal track, and the mobile robot comes to the charging station in one of the predefined steps, and performs the charging operation, practically without any interruption of the job.
Because of its freedom in motion, the robot, which is allowed to freely walk in a self-controlled manner, such as a humanoid robot or a toy robot, is associated with the difficulty of the position detection and alignment of the robot when the robot is set into the charging station.
Accordingly, it is an object of the present invention to provide a charging mechanism for a mobile robot which is battery-driven in a self-controlled fashion.
It is another object of the present invention to provide an excellent charging mechanism for a mobile robot which is battery-driven and freely and tracklessly moves within a work space.
It is yet another object of the present invention to provide an excellent charging mechanism which performs an charging operation using a charging station to charge the mobile robot which is battery-driven and freely and tracklessly moves within a work space.
It is yet another object of the present invention to provide an excellent charging mechanism which accurately and reliably establishes an electrical connection between a charging station and a mobile robot which stops at the charging station for a charging operation there.
In a first aspect of the present invention, a charging system for a mobile robot includes the mobile robot that is battery-driven and moves in a self-controlled way within a work space, and a charging station for accommodating the mobile robot for a battery charging operation. The charging system includes visible recognition data arranged in a predetermined location of the charging station, an image pickup unit mounted on the mobile robot, a calculating unit for calculating a range and a bearing from the mobile robot to the charging station, based on an image picked up by the image pickup unit, and a searching unit for causing the mobile robot to search for the charging station, based on the calculation result provided by the calculating unit.
In accordance with the first aspect, the mobile robot searches for the charging station based on the image picked up by a camera, with the visible recognition data arranged on the predetermined location on the charging station, as a target. The charging operation of the mobile robot moving on a non-tracked area is thus automated.
A communication unit for performing data exchange between the mobile robot and the charging station may be arranged. The communication unit may use any of interface protocols such as the RS-232C, IEEE1284, USB, i-Link, IrDA. The communication unit may be used for a guiding operation (for accurate alignment) when the mobile robot is received into the charging operation, or to notify of the start and end of charging.
The visible recognition data may be a print medium glued onto the surface of the charging station. A plurality of print media may be glued onto the surface of a three-dimensional object, such as a cylinder, a quadratic prism, or a sphere. In this way, the mobile robot detects the visible recognition data from a plurality of directions, and thus approaches to the charging station from various directions.
The visible recognition data may be displayed on a screen of a display unit. The visible recognition data is dynamically used in a manner that prevents the visible recognition data from being merged into the environment of the workspace. The visible recognition may be changed in response to a range from the mobile robot.
The visible recognition data may be a combination of colors and patterns. The visible recognition data may be a two-dimensional bar code or other visible marks.
By arranging the visible recognition data on an elevated portion of the charging station, the mobile robot detects the charging station from a far distance.
At least one of the charging station and the mobile robot may include an indicator indicating the condition of a battery, such as xe2x80x9cNow chargingxe2x80x9d, xe2x80x9cCharging complete (with a battery fully charged)xe2x80x9d, or xe2x80x9cAbnormal chargingxe2x80x9d.
The charging station further includes a transmitter that transmits at least one of light ray, infrared ray, sound wave, ultrasonic wave, radio wave, and magnetic field, and the mobile robot includes a receiver for receiving the wave transmitted from the transmitter. In such a case, the calculating unit calculates the range and the bearing from the mobile robot to the charging station, based on at least one of the image provided by the image pickup unit and data received by the receiver. The charging station is accurately and quickly searched for.
Preferably, the wave transmitted by the transmitter is easily discriminated and separated from other signals created within the work space.
The mobile robot may include a head unit which performs a scanning motion with respect to a torso unit, and at least one of the image pickup unit and the receiver is arranged on the head unit. The charging station is thus easily detected through the scanning motion.
The transmitter may transmit at least two signal waves, from among light ray, infrared ray, sound wave, ultrasonic wave, radio wave, and magnetic field, and the receiver may switch the received signal in response to the range between the charging station and the mobile robot. The robot searches for the charging station using a sound wave, having diffractive property, in a far range where obstacles are dispersedly present midway, and switches to light ray or infrared light ray, having rectilinear propagation property, for precise searching in a near range.
The transmitter may project a light ray through a slit, and may change the pattern of the slit depending on the direction of light projection. With this arrangement, the mobile robot approaches the charging station from a plurality of directions with the single transmitter.
The transmitter may transmit at least two signal waves that are different in output intensity and frequency component. When a high-frequency signal is transmitted at a high intensity while a low-frequency signal being transmitted at a low intensity, an area where the high-frequency component only is received is considered to be relatively far from the charging station. When the mobile robot enters an area where a low-frequency component is received, the receiver detects that the mobile robot is closer to the charging station.
The charging station may include a communication unit for exchanging data with a device other than the devices of the charging system. The communication unit is a network interface card (NIC), for instance, and an external host system may remote-control the charging station through a network.
The transmitter may be arranged external to the charging station. The charging station may be searched for using a GPS (Global Positioning System).
The mobile robot may be of the four-footed type which quadrupedally walks like a dog, and includes a power connector on the abdomen of the torso unit thereof, the charging station may include a concaved receptacle, and a power connector arranged on the inner bottom portion of the receptacle, and the receptacle may support the mobile robot in the lying down position thereof.
The charging station may include, on the wall thereof, color patterns painted in at least two colors, and the mobile robot may search for the charging station, based on the positional relationship of the color patterns in an image provided by the image pickup unit.
The mobile robot may be of the four-footed type which quadrupedally walks like a dog, and may include a power connector on the hip portion of the torso unit thereof, the charging station may include a receptacle with a bowl-shaped concave, and a generally semi-spherical projection on the generally central position of the bowl-shaped concave, and the receptacle may support the mobile robot in the sitting position thereof.
The mobile robot may be of the four-footed type which quadrupedally walks like a dog, and may include a power connector on the hip portion of the torso unit thereof, the charging station may include a receptacle with a bowl-shaped, rotationally symmetric concave, and a generally semi-spherical, rotationally symmetric projection on the generally central position of the bowl-shaped concave, and the receptacle may support the mobile robot in the sitting position thereof at any angle.
The charging operation metaphorically represents feeding the dog in the sitting position thereof, and is interesting in the entertainment point of view.
The mobile robot may have a tapered portion on at least one of a head unit, and shoulders and hip portions of a torso unit, and the charging station may includes a generally U-shaped structure having an inner wall which receives the tapered portion formed on the mobile robot. The charging station may include a generally U-shaped structure having an inner wall which receives the tapered portion formed on the mobile robot, and on the deepest inside position of the U-shaped structure, a lip having a connector arranged on the top surface thereof. Each terminal of the connector may extend inwardly deeply into the U-shaped structure.
The mobile robot may be ambulatory, and an electrode terminal may be arranged on the sole of at least one foot. The electrical connection is established in normal walking.
The charging system may include at least one electromagnet for generating a magnetic field that connects and disconnects the connector of the mobile robot to and from the connector of the charging station.
The charging station may include a drive mechanism for placing the mobile robot in an appropriate engagement position therewith. With this arrangement, the mobile robot needs no precise alignment mechanism, the required specifications of the robot is made less severe, and the weight and cost of the mobile robot are reduced.
The charging station may include a generally U-shaped structure that receives the mobile robot, and a grip unit for gripping the mobile robot within the U-shaped structure. The charging station may be used as a carrying case with the mobile robot gripped therewithin. The U-shaped structure of the charging station protects the mobile robot against impacts that may be applied thereon when in transit.
The mobile robot may be of the type that quadrupedally walks like a dog, and the charging station may have a kennel-like configuration, and at least one connector may be arranged on the inner wall of the charging station.
In a second aspect of the present invention, a method for searching for a charging station, based on a signal wave transmitted by a transmitter arranged external to the charging station in a charging system including a mobile robot that is battery-driven and moves in a self-controlled way within a work space, and the charging station for accommodating the mobile robot for a battery charging operation, includes the steps of teaching the position of the charging station based on the signal wave from the transmitter after the mobile robot has been once placed on the charging station, and searching for the charging station by calculating the range and bearing to the charging station, based on the signal wave from the transmitter, with the mobile robot at any position within the work space.
In a third aspect of the present invention, a method for searching for a charging station, based on a signal wave transmitted by a transmitter arranged external to the charging station in a charging system including a mobile robot that is battery-driven and moves in a self-controlled way within a work space, and the charging station for accommodating the mobile robot for a battery charging operation, includes the steps of storing beforehand, in a memory of the mobile robot, the position information of the charging station with respect to a reference position set in accordance with the position of the transmitter, and searching for the charging station by calculating the position of the mobile robot with respect to the reference position, based on the signal wave from the transmitter with the mobile robot at any position within the work space, and reading the position information from the memory to calculate the range and the bearing to the charging station.
In a fourth aspect of the present invention, a method for searching for a charging station, based on a signal wave transmitted by a transmitter arranged external to the charging station in a charging system including a mobile robot that is battery-driven and moves in a self-controlled way within a work space, and the charging station for accommodating the mobile robot for a battery charging operation, includes the calculating step in which the mobile robot calculates the position thereof with respect to the reference position set in accordance with the position of the transmitter, based on the signal wave from the transmitter, the calculating step in which the charging station calculates the position of thereof with respect to the reference position, based on the signal wave from the transmitter, the communicating step in which the charging station communicates the position information thereof to the mobile robot, and the searching step in which the mobile robot searches for the charging station by calculating the range and bearing to the charging station through relative relationship between the positional information.
In a fifth aspect of the present invention, a mobile robot being ambulatory and having at least a torso unit and at least two foot units, includes an electrode terminal for power feeding, at the end of at least one of the two foot units. With the arrangement of the mobile robot, the electrical connection between electrodes is established in normal walking.
In a sixth aspect of the present invention, a mobile robot being ambulatory and having at least a torso unit and at least two foot units, includes an electrode terminal for power feeding, on one of the abdomen of the torso unit and the back of the torso unit.
In a seventh aspect of the present invention, a mobile robot being ambulatory and having at least a torso unit and at least two foot units, includes an electrode terminal for power feeding, at the end of the tail. With this arrangement, the electrical connection between electrodes is established by a charming action such as the wagging of the tail.
In an eighth aspect of the present invention, a connector having a generally semi-spherical projection, is cut into at least a tip thereof and one frustohemispherical slice, each serving as a connection terminal. The tip of the generally semi-spherical projection terminal may serve as a signal line, and the frustohemispherical terminal may serve as a power line. With this arrangement, an erratic connection between connectors is duly prevented.
In a ninth aspect of the present invention, an electrical connection structure performs electrical connection with connectors mutually in contact, wherein one connector is probe-like, and the other connector is mesh-like, and wherein the electrical connection is established with the probe-like connector is inserted into the mesh-like connector at any position. The probe-like connector may have a plurality of terminals arranged along the longitudinal direction thereof, and the mesh-like connector may have a plurality of layers.
In a tenth aspect of the present invention, and electrical connection structure performs electrical connection with connectors mutually in contact, wherein the electrical connection structure includes at least one electromagnet which connects and disconnects one connector to and from the other connector.
These and other objects, features and advantages will be readily understood from the following detailed description when read in connection with the drawings.